Power operated typewriter



March 17, 1936. R T BROCKMAN 2,034,387

POWER OPERATED TYPEWRI TER Filed Oct. 24, 19:52 7 SheecLs-Sheet 1 Q:Wafer? 7. Brae/imam 'March 17, 1936. 1-, BROCKMAN 2,034,387

POWER OPERATED TYPEWRITER W Filed Oct. 24, 1932 7 Sheets-Shet 2 INVENTORFairer) Z'Broc/rman BY Xe/W, M, WW

ATTORNEY$ March 17,1936. T, BRQCKMAN 2,034,387

POWER OPERATED TYPEWRITER Filed Oct. 24, 1932 7 Sheets-Sheet 4 INVENTORPoerf 77 Brae/1mm mf m' ATTORN EYS March 17, R T BROCKMAN POWER OPERATEDTYPEWRITER Filed Oct. 24, 1932 7 Sheets-Sheet 5 INVENTOR Puller)FBmc/rman Jan w%a7 ATTORNEYS March 17, 1936. R T, BROCKMAN POWEROPERATED TYPEWRITER Filed 001;. 24, 1932 Fig. 5.

7 Sheets-Sheet 6 INVENTOR 5w Z'Bmckmafi M Mm 2 ATTORNEYS March 17, 1936.R BRQCKMAN 2,034,387

POWER OPERATED TYPEWRITER Filed 001:. 24, 1932 7 Sheets-Sheet 7 INVENTORATTORNEYS Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE POWEROPERATED TYPEWBITER Application October 24, 1932, Serial No. 639,249

7 Claims.

This invention relates to a power operated typewriter. It concerns aconstruction in which various parts of a typewriter are operated bypower, particularly the type bar action, the case shift, the back spacerand the escapement mechanism. It also concerns an improved means forpreventing rebound of the type bars of a typewriter.

The general object of the invention is to provide an improved poweroperated typewriter.

A more particular object is to provide an improved power operated typeaction.

Another particular object is to provide an improved means for preventingrebound of the type bars of a typewriter.

A further object is to provide an improved case shift mechanism.

Still another object is to provide an improved back spacing mechanism.

Other objects and advantages of the invention will appear from thefollowing specification and drawings.

An embodiment of the invention is shown in the accompanying drawings inwhich:

Figure 1 is a perspective view of a portion of the machine showingparticularly the operating mechanism for the type bars.

Fig. 2 is a partial left side elevation of the type bar operatingmechanism, the parts being shown in normal position.

Fig. 3 is a partial left side elevation showing particularly thekeyboard and certain of the control keys.

Fig. 4 is a partial left side elevation showing th type basket and theshifting mechanism therefor.

Fig. 5 is a partial left side elevation illustrating both the operatingmechanism for the type bars and case shift mechanism.

Fig. 6 is a detail view showing portions of the back spacing mechanism.

Fig. 7 is a fragmentary view of portions of Fig. 5 showing them in theposition they occupy at the moment the power operation of the type baris released.

F. g. 8 is a view similar to Fig. 2 but showing the parts in positionwith a key depressed and with the type bar actuator about to operate.

The typewriter is driven by an electric motor It (Fig. 1) which rotatesa worm ll meshing with a worm wheel l2 fixed to a main drive shaft l3,whch is suitably journaled in the typewriter frame. While the machine isin use the motor ro'ates the drive shaft l3 continuously and power istaken from this shaft to operate various parts of the typewriter. Eachof the parts or groups of parts will be described separately,

Power operated type bar action The type bars are driven to printingposition by being momentarily connected to the power shaft and thenautomatically disconnected prior to the time that they reach printingposition, the momentum of the type bars being depended upon to cause thebars to move to final printing position. A plurality of type bars areprovided but since the mounting and driving mechanism for each is alike,the description and illustration will be confined to the type bar forthe sake of conciseness and simplicity.

Referring to Fig. l, the machine is provided with a plurality of typebars, such as the bar It, having lower case type It and upper case typeH. The type bar i5 is pivoted on a shaft l8 carried by a shiftable typebasket that will be later described. Connected to the lower end of eachtype bar is a link l9 which is also connected to one arm of a bell cranklever 20 having a second arm provided with a cam slot 21. The bell cranklever is pivoted on a shaft 22 and rocked by means of an actuator 23pivoted on a shaft 2| and carrying a cam roller 25 operating in the camslot H in the arm of the bell crank lever 20. When the bell crank lever26 is rocked clockwise from the position of Fig. 1, the link I9 ispulled forward and the type bar I 5 is moved toward printing position. Aspring 26 is connected between the actuator 23 and bell crank 28 to urgethese parts to the position of Fig. 1.

The type bars are moved to printing position by an operating bail 21which is adapted to engage the actuators 23 for each of the type bars.When a type key is depressed, the actuator for the type barcorresponding to the depressed key is moved into the path of theoperating bail and the bail is connected to the power shaft. This causesthe bail to be rocked and the type bar to be driven to printingposition. After the type bar has moved a predetermined distance, theoperating bail is automatically disconnected from the power shaft andthe type bar is also automatically disconnected from the bail. Themechanism for accomplishing these results is as follows:

Pivoted to the actuator 23 is a pawl 30 urged counterclockwise as viewedin Fig. 1 by a spring 3 l This pawl has a shoulder 32 adapted to engageover the operating bail 2? when the pawl is moved clockwise from itsFig. 1 position.

The pawl '39 is moved clockwise to bail-engaging position by an abutmentarm 33 which is an integral part of a rock lever 35 that is rockedcounterclockwise from its Fig. 1 position when a type key is depressed.Referring to Fig. 3, it will be observed that the rock lever 34 is anelbow lever pivoted on a shaft 35. The lever carries a stud 36 engagingin a slot 31 in the end of a key lever 38 which is pivoted on a shaft39. The key lever 38 projects forward to where the stem 39 of a type key48 is connected to it. The key lever 38 is urged counterclockwise tonormal position by a spring 4| and depression of more than one key at atime is prevented by a series of balls 42 mounted in a raceway 43, therebeing just space enough between the balls to permit one key lever at atime to enter between them.

, From Fig. 3 it will be clear that, when the type key 40 is depressed,the lever 38 is rocked clockwise, which rocks the lever 34counterclockwise and moves the abutment arm 33 rearward to move the pawl38 to bail-engaging position.

The operating bail 21 is momentarily connected to the power shaft |3 bydepression of a. type key and, for this purpose, the rock lever 34 isprovided with a pawl 45 (Fig. 1) pivoted to it and urgedcounterclockwise by a spring 46 against a limit stud 41. This pawl has anose 48 normally positioned in front of the edge of a bail 50 pivoted onstuds 5| on stationary parts of the machine. When the rock lever 34 ismoved counterclockwise from its Fig. 1 position, the nose 48 of pawl 45engages the bail 50 and rocks it clockwise to momentarily connect theoperating bail 21 to the power shaft I3.

The operating bail 21 is carried by two arms 52 and 53 which are fixedto a sleeve 54 rotatably mounted on the power shaft l3. The arm 52carries two studs 55 and 56 which support a plate 51 on which is pivotedat 58 a pawl 68 urged clockwise, as viewed in Fig. 1, by a spring 6|connected to a stud 62 on the pawl. This pawl is adapted to engage aratchet wheel 63 fixed to the power shaft I3. The pawl is urged byspring 6| toward ratchet-engaging position but is normally preventedfrom engaging the ratchet wheel by a plate 64 on the end of a detent 65pivoted at 66 and urged clockwise by a spring 61 against a limit stud68. The detent 65 has a forward projection 10 positioned over ashouldler 1| on a releasing member 12 pivoted on a stud 13 and urgedcounterclockwise by a spring 14, as well as by spring 61, against alimit stud 15 carried by the supporting plate 51. The stud 13 on whichthe release member 12 is pivoted is carried by an arm 16 pivoted on ashaft 11. A link 18 connects the arm 16 with an arm 19 integral with oneside of the bail 50.

When a type key is depressed, the rock arm 34 moves counterclockwise, asviewed in Fig. 1, and the bail 50 is rocked clockwise. This pulls thelink 18 upwardly which moves stud 13 with release member 12 upwardly.The shoulder 1| on the release member engages the projection 10 ofdetent 65 and rocks the detent counterclockwise so as to free the pawlwhich is immediately urged by spring 6| into engagement with therotating ratchet wheel 63. The ratchet wheel picks up the pawl and movesit, together with the plate 51, the studs 55-56 and the operating bail21, counterclockwise about the axis of the drive shaft 3. When the arm34 was rockedcounterclockwise by depression of the type key, the pawl 30on the actuator 23 was positioned over the operating bail 21.Accordingly, when the operating bail is moved upward, as abovedescribed, the actuator 23 is rocked clockwise as viewed in Fig. 1 andthe type bar I5 is moved toward printing position.

An advantage of the above construction to be noted at this point is thatthe engagement between the operating bail 21 and the driving ratchet 63is not dependent upon the character of depression of the type key. Nordoes the type key have to tension any operating springs. The type keymerely tensions the digit key lever spring 4| and moves the detent 65 torelease pawl 60 which is moved to engaging position by the spring 6|.This means that the engagement between the pawl 60 and the ratchet 63 isof the same character no matter whether the key is depressed slowly orvery rapidly.

After the type bar has been moved a predetermined distance, theoperating bail is automatically disconnected from the power shaft. Forthis purpose the following construction has been provided:

The spring 6| (Fig. l) which urges the pawl 60 clockwise is connected toa stud 80 on a pawlcontrolling member 8| pivoted at 82 on the plate 51.The spring 6| normally urges member 8| counterclockwise against thelimit stud 15, the member being provided with a tail piece 83 forengagement with stud 15. It will be observed that the line of action ofthe spring 6| is below the pivot 58 of the pawl 60 so that the pawl isurged clockwise, or in a direction to engage the ratchet wheel 63. a

The pawl-controlling member 8| has a second tail piece 84 which ispositioned so that, when the supporting plate 51, on which the pawl 60and the member 8| are mounted, is moved counterclockwise from theposition of Figs. 1 and 5, the tail 84 will engage a stud 85 (Fig. 5) onan arm 86 which may be adjustably positioned by means of a worm 81 thatcan be rotated manually from the forward part of the machine. When thetail 84 of the member 8| strikes stud 85, the member 8| is rockedclockwise about its pivot 82 and the tail 83 of member 8| strikes stud62 on pawl 60. This quickly and suddenly knocks the pawl 60 out ofengagement with ratchet wheel 63. At the time that member 8| rocksclockwise, the stud 80 on said member moves upward and the line ofaction of the spring 6| moves above the pivot 58 of the pawl 60 with theresult that the spring tends to hold the pawl in retracted position as,

well as to aid in retracting it.

It is to be observed that the pawl 60 is carried by a plate 51 whichmoves about the same axis as the ratchet wheel 63 so that no relativemovement between the pawl and the ratchet wheel occurs during thedriving action. This avoids wear between the parts such as would occurif these parts moved relatively while in driving engagement. pawl andratchet wheel until the pawl is suddenly hit by the member 8| tosuddenly and quickly move it to released position.

The automatic disconnection preferably occurs slightly before the typebar reaches printing position and the momentum of the bar is dependedupon to carry it to its final printing position, the point ofdisconnection being regulated by varying the position of stud 85 (Fig.5).

When the pawl 60 is released from the ratchet wheel 63 the operatingbail 26 with its associated parts returns to normal under the influenceof its spring 88 (Fig. 2). As these parts, including the member 8|,return clockwise, the tail 84 of member 8| strikes a stationary stud 89(Figs. 1 and 5) carried by one of the plates of the ma- No movementoccurs between the chine which rocks the member 8| counterclockwise toits normal position. The line of action of the spring fil moves belowthe center of the pivot 58 of pawl 60 and the spring tends to rock thepawl into engagement with the ratchet wheel 63. Such engagement isprevented, however, by the detent 65 which moved to normal positionwhile the type bar was being moved to printing position. When the plate51 was moved counterclockwise during the type bar operating action, thestud on said plate engaged a cam surface 90 on the detent-releasingmember 12 and rocked said member clockwise so as to move its shoulder Hfrom beneath the projection 10 on detent 65. Thereupon the spring 6'!moved the detent 65 to normal position so that, when the bail and itsassociated parts are returned as above described, the

detent was in position to arrest the pawl 60 in the Fig. 1 position.

It is to be observed that the above described movement of member 12 alsoprevents more than one operation of the type bar even though the typekey may be held depressed. For example, when the type bar is movedtoward printing position, the member 12 is moved clockwise and releasedfrom detent 65. If the type key is held depressed, the member 12 is heldelevated and it is out of engaging position with projection I0 on detent65 so that the control of the detent is lost. The detent returns tonormal and prevents a second engagement of pawl 60 with ratchet wheel63. If the type key is held depressed, it cannot result in a secondoperation of the type bar because the pawl 65 cannot be released untilthe key is released and depressed again.

A second means is provided that prevents more than one operation of atype bar when a type key is held depressed. Referring to Fig. l, theactuator 23 is provided with a stud 9| which when the actuator is movedby bail 21, engages a cam surface 92 on the pawl 45 to rock the pawlclockwise out of engagement with the ball 50. The bail 50 can thenreturn to normal under the influence of spring 14. depressed the lever34 is held in its rear position where the nose 48 of the pawl 45 will beunder the ball 50. As long as the lever 34 is held in this position,which it would be if the key were held depressed, the pawl 45 cannotreengage the bail and a second type bar driving action of the actuatorcannot occur. because the bail 50, the link 18 and the member. 12 forreleasing the detent 65 cannot be moved a second time until the type keyis released and then depressed again.

The provision of two releasing means as above described is not necessaryand one may be omitted if desired. The preferred one at the present timeis the release of pawl 45.

Rebound prevention Preventing the type bars from rebounding in a poweroperated machine is one of the things that contributes to the success ofthis type of machine.

In key operated machines the keys are driven to printing position by theforce of the key de pression and they are returned by springs. Therapidity of action of a key operated machine usualy depends upon therapidity with which the type bars are retmned to normal by the springs.If quick action is desired the springs must be made strong. On the otherhand, if the springs are made strong, the key action becomes hard. Alsowhen the springs are made strong, the type bars often rebound when theyare brought back to normal, with the result that they interfere with oneanother and jamming occurs.

In power operated machines hard key action is not an objection becausethe type bars are If the type key is held moved to position by power.The retm'ning springs may, accordingly, be made relatively strong, but,when they are made strong, the rebound becomes greater and difliculty isencountered by jamming. Control of this rebound action is one of theimportant factors in the speed of a power operated machine.

Rebound is prevented in the present machine by a novel construction oftype bar action which effectively prevents rebound without requiringthat special type bar rests or other rebound preventers be used.

Referring to Fig. 2, it will be observed that the slot 2! in the bellcrank lever 26 is shaped so that the rear end "M of the slot, that is,the part through which the cam roller 25 moves during the initialmovement of the actuator 23, is approximately concentric with the axisof the shaft 2 3 about which the actuator 23 rocks. As the actuator 23is rocked counterclockwise from the position of Fig. 2, very littlemovement is given to bell crank lever Ell during the initial movement ofthe actuator, but, as soon as the cam roller 25 moves out of the firstpart Hill of slot 2|, the bell crank lever is given a sudden movement bythe part Ml of slot 28 to throw the type bar to printing position. Uponthe return of the type bar it will be observed that it is returnedquickly during its initial movement and is then "eased or walked intoits final position owing to the fact that, while the stud is returningthrough the part 800 of slot 2| no appreciable movement of bell crank 20occurs. It is also to be noted that the portion "In of the slot 2| isapproximately concentric with the shaft 24 and that the arm of actuator23 is approximately at right angles to the portion I00 of the slot. Anytendency of the bell crank 20 to move while the cam roler 25 is in theportion Hill of slot 2| is resisted by the actuator 23 in a direct linebetween roler 25 and the axis 24. In other words, rebound of the bellcrank 20, induced by rebound of type bar 15, is effectively prevented,because any force tending to rock the bell crank 20 is transmitted toactuator 23 in a direction longitudinal of said actuator and does nottend to rock it about its axis 24.

Accordingly, when the type bar is returned, it is returned quickly andthe actuator then moves into the portion I00 of the slot 2| such thatthe type bar is held against rebound movement. The type bar is quietlywalked" into final position and held against rebound without, however,destroying the eifective action of the actuator in again moving the typebar to printing position.

Escapement mechanism Each time a type bar is moved to printing position,the escapement mechanism is operated as follows:

Referring to Fig. 2, a 1m: no is provided Fig. 2 position the bail H3 isrocked clockwise and the link I") moved forward to operate theescapement.

Case shift The typewriter is changed from upper to lower case positionand vice versa by power and this power is used to accomplish the shiftin both directions. In the embodiment of the invention illustrated, thetype basket is shifted instead of the platen.

Referring to Fig. 4, the shaft I8 on which the type bars I5 are pivotedis carried by a type bar segment I attached to a movable supportingplate I2I. The type bar segment carries a suitable type bar guide I22for guiding the type bars during their final movement to printingposition.

The supporting plate I2I carries an upper roller I23 and a lower rollerI24 on each side which travel between substantially vertically arrangedshafts I25 supported by the stationary plates I26 and I21 of themachine. The weight of the type bar basket and the type bars togetherwith the supporting plate and associated parts is counterbalanced by aspring I28 attached at its upper end to a stud I29 on the stationaryplate I26 and at its other end to the end of a shaft I30 on which thelower roller I24 is mounted. The arrangement is such that the springcounterbalances the weight of the type bar basket and associated partsso that the type bar basket is substantially balanced in all of itspositions.

The type basket is moved from lower to upper case position and viceversa by means of a link I3I connected at its upper end to a lug I32 onthe supporting plate I2I and at its lower end to an arm I33 fixed to ashaft I34. Fixed to this shaft is a bell crank lever I35, one arm ofwhich has a spear-like head I36 cooperating with a stud I31 on a detentI38 urged clockwise by a spring I39, the arrangement being such that thedetent tends to hold the type basket in either its upper or its lowerposition.

The other arm of bell crank I carries a stud I40 on which is pivoted adouble-pointed pawl I4I adapted to engage a ratchet wheel I42 fixed tothe power shaft I3. The pawl I has one lateral lug I43 on its forwardside for engaging the ratchet wheel I42 and another lateral lug I44 atits rear for engaging said ratchet. The pawl has a slot in its upper endprovided with a front abutment surface I45 and a rear abutment surfaceI46, both of said abutments being adapted to engage a collar I41 onshaft I3.

The case shift pawl MI is positioned for engagement with the ratchetwheel I42 by means of a. link I connected at its rear end to the lowerend of the pawl MI and, at its forward end, to a lever I5I pivoted on astud I52 and provided with an abutment face I53. A stud I54 on an armI55 is adapted to engage the abutment I53, the arm I 55 being urgedcounterclockwise as viewed in Fig. 4 by a spring I56. The arm I55 ispivoted on one arm I51 of a bell crank lever pivoted at I58 and having asecond arm I59. The movement of bell crank I51I59 is limited by a. studI60 positioned in an opening I6I in the bell crank lever. Connected tothe arm I59 of the bell crank lever is a link I62 which extendsforwardly (Fig. 3) where it is connected by a pinand-slot connection toone arm I63 of another bell crank lever pivoted on a shaft I64 and urgedcounterclockwise, as viewed in Fig. 3, by a spring I65. The other armI66 of this bell crank lever extends forwardly and is provided with acase shift key top I61.

When the typewriter is'in its normal lower case position, the parts arein the position illustrated in Fig. 3 and in full lines in Fig. 5. Thestud I54 engages the abutment surface I53 below the pivot I52 and thespring I56, acting on arm I 55, urges the lever I5I clockwise. Thistends to pull the link I50 forwardly but such action is limited by theengagement of abutment face I45 of pawl I M with the collar I41 as shownin Fig. 5. At this time thelug I43 is out of the path of the teeth ofratchet wheel I 42.

When the case shift key I61 is depressed, the bell crank I66-I63 isrocked clockwise which pulls the link I62 forward. This rocks the bellcrank I59-I51 clockwise and moves the stud I54 upwardly from the fullline position of Fig. 5 to the dot-and-dash position of said Fig. 5.When the stud I54 moves above the pivot I 52, the action of spring I56on arm I55 rocks the lever I5I counterclockwise which thrusts the link I50 rearward. This rocks the pawl I4I clockwise and causes the lug I44 toengage the rotating ratchet wheel I 42. The ratchet wheel then picks upthe pawl HI and moves it downward which rocks the bell crank I35counterclockwise and pulls the type basket link I 3I downward to lowerthe basket to upper case position as shown in full lines in Fig. 4. Asthe parts move to upper case position, the spear head I36 moves from theposition of Fig. 5 to that of Fig. 4 to hold the type basket in theposition to which it is moved.

The pawl MI is automatically disconnected, after the type basket hasbeen moved, by engagement of the abutment face I 46 on the pawl with thecollar I41. As the pawl moves downward, the abutment I46 engages collarI41 and guides the pawl in a straight line downward so that iteventually is carried out of engagement with the ratchet wheel, theparts being proportioned so that this occurs at just the right moment.

As long as the case shift key is held depressed, the type basket remainsin its upper case position but, upon release of the case shift key, thepower operated mechanism comes into play to positively return the typebasket to lower case position.

When the case shift key is released, the spring I65 (Fig. 3) returns.the bell crank I63I66 counterclockwise to normal, the link I62 isthrust rearward, the bell crank I59I 51 rocked counterclockwise and thearm I55 with its stud I54 pulled down to its Fig. 3 position. As thestud I54 moves downwardly on the abutment surface I53 below the pivotI52, the action of spring I56 rocks the lever I5I clockwise and pullsthe link I50 forward.

This rocks the pawl I4I counterclockwise and moves the lug I43 intoengagement with the rotating ratchet wheel I42. The ratchet wheel picksup the pawl and pulls it upward which rocks the bell crank I35clockwise. This rocks the shaft I34 clockwise and pushes the type basketlink I3I upward to move the type basket to its upper position, which isits lower case position. As the type basket moves upwardly, the spearhead I36 moves from the position of Fig. 4 to that of Fig. 5 to hold thetype basket in the position to which it is moved.

The pawl MI is automatically disconnected from the ratchet wheel I42 bythe engagement of the abutment surface I45 on the pawl with the collar I41. As the pawl moves upward with the ratchet wheel, the abutmentsurface engages collar I41 and the pawl is guided in a straight line sothat it is eventually cammed out of engagement with the ratchet wheel.The parts are proportioned so that this occurs at the right moment.

From the above, it will be observed that the power shaft I3 is utilizedto change the machine both from lower to upper case position and fromupper to lower case position and that neither springs nor gravity isdepended upon for either movement.

A case shift lock is provided in the form of a case shift lock key I19(Fig. 3) carried by one arm I1I of a bell crank lever pivoted on shaftI64. The other arm I12 of this bell crank lever extends upwardly and ispositioned to-the rear of a stud I13 on the link I62. The bell crank armI1I is provided with a square stud I14 adapted to engage under ashoulder I15 on a latch I16 urged counterclockwise by a spring I11.

When the case shift lock key I19 is depressed, it rocks the bell crankI1I-I12 clockwise and pulls the link I62 forward to condition themachine so that the power shaft will move the type basket to upper caseposition. After the stud I14 moves past the shoulder I15 on latch I16,the latch is snapped over the stud to hold the bell crank I1II12 in itsmoved position. As long as it is held in this position, the type basketremains in upper case position.

The case shift lock may be released by depressing the regular case shiftkey I 61. The latch I16 has a tail I18 positioned in the path of thearm. I66 on which case shift key I61 is mounted. When key I 61 isdepressed, arm I66 engages the tail I18 of latch I16 and moves the latchto released position.

The pin and slot connection between the link I62 and lever I63 permitsthe link I62 to be moved a short distance when the case shift lock keyI10 is depressed without carrying the case shift key I61 down with it,otherwise the downward movement of the case shift key I61 would causethe arm I66 to engage the lug I18 and prevent the latch I16 from lookingthe case shift lock key I 16 in depressed condition, but with thisconstruction, it will be evident that the case shift lock key willremain in locked down position until the case shift key I61 is depressedmanually to release the latch I16 at which time the case shift lock keywill be restored upwardly by a spring I19 until limited by a comb plateI19.

Back space mechanism The back space mechanism includes a pawl I89 (Fig.6) adapted to engage a rack II on the paper carriage in such a way that,when the pawl is actuated, the carriage is moved backward one step. Thispawl is operated by means of a link I82 (Fig. which is adapted to beengaged with the ratchet wheel I42 driven by power shaft I3.

The link is urged clockwise as viewed in Fig. 5 by a spring I83, themovement being limited by an abutment I84 on the link which engages a.collar I85 on shaft I34.

The link has a lateral driving lug I86 provided with a sharp edgeadapted to engage the ratchet wheel I42.

For the purpose of moving the link into driving engagement with theratchet wheel, the link is provided with a stud I96 normally positionedabove a shoulder I9I on one arm 0f a lever I92 pivoted by a pin-and-slotconnection I93 to one end of an arm I94 and urged clockwise by a springI95. The arm I94 is one arm of a bell crank lever pivoted at I96 andurged counterclockwise by spring I96'. The other arm I91 of this bellcrank is connected by a link I98 to a second bell crank lever I99 (Fig.3) pivoted on the shaft 39. The bell crank I99 carries the back spacekey 260.

When the back space key 260 is depressed, bell crank lever I99 is rockedclockwise, link I98 is pulled forward, bell crank I91-I94 is rockedclockwise, and the releasing lever I92 is moved upward. This moves thelink I82 upward and causes the lug I86 to engage ratchet wheel I42. Theratchet wheel picks up the link and moves it forwardly to operate theback space mechanism one step.

The link I82 is automatically disconnected from the ratchet wheel I42after the carriage has been back spaced a single step, by a lug 2Mprojecting from the lower edge of the link I82. When the rachet wheelI42 engages the lug I86, it moves the link I82 forward andcounterclockwise thereby moving the projection 20I upward until itstrikes the periphery of the ratchet wheel I62 to prevent furthercounterclockwise movement of the link I82. The link I82 continuesslightly forward until the engaged ratchet tooth frees itself from thelug I86, at which time the spring I83 pulls the link I62 back to itsFig. 5 position with the abutment I84 again resting on the collar I85.

The carriage can be back spaced only one step for each depression of theback space key 290 and means are also provided to insure of a quickupward movement of the lug I86 of the link I82 into the path of theratchet wheel I42, thereby preventing chattering that might result fromthe top of the lug I86 engaging the rotating ratchet when the back spacekey is slowly depressed. When the back space key is depressed, the pinand slot connection I93 permits the arm I94, that carries the stud I93,to move clockwise independently of the lever I92. The spring I95 urgesthe lever I92 clockwise against the stud 203 and said stud restrainsupward movement of the lever I92 by engaging the bevelled shoulder 262.When the stud I93 on the end of the arm I94 reaches the upper end of theslot in the lever I92, it starts to lift the lever I92 and because ofthe bevelled shoulder 202 the lever I92 is cammed free of the stud 203thereby enabling the spring I95 to snap the lever I 92 upward for theshoulder I9I to engage the stud I99 and move the lug I86 into the pathof the teeth of the ratchet wheel quickly without any chattering. Thelever I 92 is guided in its upward movement by its front face engagingthe stud 293. Forward movement of the link I82 carries the lug I 98 offthe shoulder I9I.

When the link I82 is released from the ratchet wheel I42, it moves backto its lower Fig. 5 position under the influence of spring I83. The studI90 is then below the shoulder I9I. Accordingly, as long as the backspace key is held depressed, the link I82, cannot be raised a secondtime for engagement with the ratchet wheel. In order to cause a secondengagement, the back space key must be released and depressed again.

I claim:

1. A power-operated, front-strike typewriter having a plurality ofpivoted type bars, an actuator for each bar, a movable operating bailfor moving said actuators to swing the type bars to printing position,said actuators being normally out of the path of said bail, poweroperating means, normally disconnected connecting means between saidpower operated means and said operating bail, a plurality of type keys,means associated with each key operable, upon the depression of a givenkey, for moving a portion of the actuator corresponding to said key intothe path of said ball, power controlling means conditioned by depressionof each of said keys for conditioning said connecting means to causesaid operating bail to be connected to said power operating means, saidconnecting means having portions acting to automatically disconnect saidbail from said power means after said bail has been moved apredetermined distance, and means operated by the moved actuator toautomatically disconnect the depressed key from said power controllingmeans as the type bar is moved to printing position to prevent more thanone operation of the type bar when the type key is held depressed longerthan necessary.

2. A power-operated, front-strike typewriter having a plurality ofpivoted type bars, an actuator for each type bar for swinging the latterto printing position, a movable bail for said actuators, said actuatorsbeing normally out of the path of said bail, power operating means,normally disconnected connecting means between said power operatingmeans and said operating bail, a plurality of type keys, a leveroperable by each type key for moving a portion of its actuator into thepath of said bail, a power controlling bail connected to saidconnecting-means and operable to condition the latter to connect saidoperating bail to said power operated means, a pivoted pawl on each ofsaid levers normally connected to said power controlling bail foroperating it upon depression of a key, and means operated by a movedactuator for disconnecting the pawl on the lever corresponding to saidactuator from said power controlling bail when said actuator is moved.

3. In a power operated typewriter, a continuously rotating ratchetwheel, a member on said machine movable in one direction to a givenposition and returnable in the opposite direction therefrom, a pawlconnected to said movable member, said pawl having one tooth adapted toengage one side of said ratchet wheel and another tooth adapted toengage the other side of said ratchet wheel, means for swinging saidpawl to cause either of its teeth to engage said ratchet wheel, andmeans acting to automatically disengage said pawl from said ratchetwheel after it has been moved a predetermined distance by the engagementof either of its teeth with said ratchet wheel.

4. In a power operated typewriter, a continuously rotating ratchetwheel, a member on said machine movable in one direction to a givenposition and returnable in the opposite direction therefrom, a pawlconnected to said member, said pawl having one tooth adapted to engageone side of said ratchet wheel and another tooth adapted to engage theother side thereof, spring means for swinging said pawl, and keycontrolled means operable to condition said spring means to cause it toswing said pawl in a chosen direction to thereby selectively engage theteeth of said pawl with said ratchet wheel to move said machine memberin a chosen direction by power, and means acting automatically todisconnect said pawl from said ratchet wheel after said member has beenmoved a predetermined distance by engagement of the selected pawl toothwith the ratchet wheel.

5. In a power operated typewriter, a continuously rotating ratchetwheel, a member movable in one direction to a given position andreturnable in the opposite direction therefrom, a pawl connected to saidmember, said pawl having one tooth adapted to engage said ratchet wheelon one side and another tooth adapted to engage said ratchet wheel onthe other side, means for swinging said pawl to engage either of saidteeth with said ratchet wheel, a slot in said pawl forming two abutmentsurfaces, and a collar in said slot adapted to engage said surfaces todisengage said pawl from said ratchet wheel after said pawl has beenmoved a predetermined distance by engagement of either of its teeth withsaid ratchet wheel.

6. In a power operated typewriter, a continuously rotating ratchetwheel, a member movable in one direction to a given position andreturnable in the opposite direction therefrom, a pawl connected to saidmember, said pawl having one tooth adapted to engage one side of saidratchet wheel and another tooth adapted to engage the other side of saidwheel, a pivoted lever connected to said pawl, said pivoted lever havingan abutment surface, a spring urged arm engaging said abutment surface,means for moving said arm to cause it to engage said abutment surfaceabove or below the pivot of said lever to selectively move said lever ineither direction to optionally move either of the teeth of said pawlinto engagement with said ratchet wheel, and means acting toautomatically disengage said pawl from said ratchet wheel after saidpawl has been moved a predetermined distance by engagement of either ofits teeth with said ratchet wheel.

'7. A typewriter having a traveling paper carriage, an escapementmechanism therefor, a power driving means including a toothed ratchetwheel, a back spacing mechanism, means for connecting said back spacingmechanism to said power drive including a pawl for effecting saidconnection and a spring operable, when tensioned, to move said pawl,means normally holding said spring against such operation, and meansincluding a back spacing key operable, upon depression of said key, tofirst tension said spring and to then automatically release said holdingmeans to permit said spring to quickly move said pawl into engagementwith said ratchet wheel to thereby connect said back spacing mechanismto said power drive without chattering.

ROBERT T. BROCKMAN.

